Automatic telephone system



OCt. 6l 1936- E, s. PETERSON AUTOMATIC TELEPHONE SYSTEM y Filed Oct. 19, 1934 6 Sheets-Sheet 1 2 a` v om Tn R. H m m@ m I E- m mm zu.H m NM m m m2: 3 om w .Sm l s l Fmmwww. lo E mm A 5h22 IEn m 202:8 mm E w ww L@ .w M 221. m e Li 3 .el zo $23 N zoiml a/ l m" Q25 .228, ,E k 9 .2: mw L ww I|||||||l NN EK EDWARD S. PETERSON ATTORNEY.

6 Sheets-Sheet 2 E. s. PETERSON AUTOMATIC TELEPHONE SYSTEM Filed oct. 19, 1934 OPumZZOU .ISOT- Oct. 6, 1936.

ATTORNEY.

oct. 6, 1936;

E, S. PETERSON AUTOMATIC TELEPHONE SYSTEM 6 Sheets-Sheet 3 Filed Oct. 19. 1954 .IY- O I .In

INVENTOR.

EDWARD S PETERSON BY Ma# ATTORNEY.

Oct. 6, 1936. E. s. PETERSON AUTOMATIC TELEPHONE SYSTEM 6 Sheets-Sheet 4 l Filed Oct. 19, 1954 NVENTOR.

EDWARD S. PETERSON ATTORNEY.

6 Sheets-Shut 5 E. S. PETERSON AUTOMATIC TELEPHONE SYSTEM Filed oct. 19, 1934 Oct. 6, 1936.

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Patented Oct. 6, 1936 UNITED STATES PATENT OFFICE AUTOMATIC TELEPHONE SYSTEM Application October 19, 1934, Serial No. 749,023

22 Claims.

The invention relates to telephone systems in general, but is concerned more particularly with semi-automatic telephone systems whereby connections between manual lines entering an ex- 5 change may be set up by automatic switches under the control of an operator at a switchboard at a remote exchange.

The main object of the invention is the production of new and improved circuit arrangements l for simplifying and improving the operation in semi-automatic magneto telephone systems of the type disclosed in application Ser. No. 676,439, filed June 19, 1933, now Patent 2,010,372, granted Aug. 6. 1935, in the name of E. S. Peterson. In l the above application connections are set up between manual magneto lines by automatic switching apparatus responsive to control exercised over a control trunk extending between the manual magneto exchange and a remote operating center. This type of system was designed to improve service in rural communities by making it possible for a remote operator, instead of a local operator, to control the connection. This equipment is intended to replace manual magneto switchboards which cannot possibly carry the cost of a local operator. Remote controlled exchanges of this type are generally referred to as R'. C. X.s. In a system of this type, the local subscriber, upon initiating a call by turning his hand generator, causes a iinder in the local exchange to find his line and signal the remote operator over a control trunk extending to the remote operating center or main exchange. The remote operator answers the call, dials back over the same control trunk, thereby establishing the desired connection to the local called line, and then rings the party. The remote operator then retires from the local connection and either the local calling or called parties can release the local connection by turning the hand generator.

Another object of the invention is the provision of improved dialling and control circuits in the operators control trunk to eliminate marginal operations which may cause trouble due to differences in ground potential between the R. C. X.

and the remote operating center.

Another object of the invention is the provision 0f means whereby common battery lines may be connected to an exchange of this type which is primarily designed for manual magneto lines.

One feature of the invention relates to the means whereby the operator is automatically disconnected from the calling line and automatically connected to the called line regardless of the idle or busy condition of the called line after the control operator has completed dialling the called subscribers number'.

Another feature relates to the repeating coil in the common equipment which enables a grounded line having its negative line conductor grounded, another grounded line having its positive line conductor grounded, and the control operator to be connected in a three way talking circuit in such a manner that the first subscribers line will not short out the second subscrbers line.

Another feature relates to the means whereby the control operator is signalled over the control trunk when all of the links of the local R. C. X. are busy, and if the control operator should release after answering this signal without supervising, such operator is automatically resignalled.

Other objects and features of the invention will be apparent upon a further perusal of the specication in connection with the detailed description of the accompanying drawings in which Figs. l to 6, inclusive, show the detailed circuits.

Referring now to Fig. l the upper left-hand circle diagrammatically represents a plurality of well known magneto substation circuits in which the ringers thereof may be connected to either line conductor and ground or may be bridged across the line conductors. The lower left-hand circle diagrammatically represents a plurality of common battery substation circuits having their ringers connected to either line conductor and ground or bridged across the line conductors. LC shows the line circuit of one of the regular magneto lines, and LC-I the line circuit for one of the common battery lines. Relays 5I and 52 show a so-called line adapter for enabling the common battery line to be connected to an exchange of'this type. The nder switch F is of the well known rotary type in which the Wipers move step by step on the deenergization of its motor magnet and in which the wipers remain in the position last used.

Fig. 2 represents the local connector permanently associated with the finder F. YThe local connector is of the well known Strowger type having vertical and rotary movement. The normal post spring TOLL-PS-I operates when the connector is raised opposite the level in which the toll trunks terminate.

Fig. 3 shows the distributor for preselecting idle local finder-connector links, such as the one shown in Figs. 1 and 2. The distributor comprises a well known step-by-step rotary switch vsimilar in construction to the finder F and an associated group of relays.

Fig. 4 shows the common equipment compris- I y relays of Fig. 4a are connected in the circuit by connecting corresponding terminals indicated by circles. Y

Fig. 5 shows a supervisory switch for enabling Vthe remote operator to supervise the apparatus in the R. C. X. This switch is alsoof the Awell known rotary step-by-step type. A local emergency operating center indicated by the square in the center of the drawing is somewhat similar to the remote operating center shown in the dotted rectangle in the lower left-handcorner. The

' equipment located at the remote operating center comprises the usual operators headset, call'- in'g'devic'e CD, repeating coil RC2, an answer key, a two-way monitor and ring Vvkey, and signalling Y means.

AFigffsl'rowsa jack endedtoll trunk terminating in the'remote operating center or another distant exchange. The equipment comprises the usual jack J Vand drop, therepeating coil RC4 and the ringing zkey. The tolltrunks are Vaccessible from the toll levels of the localconnector banks. The toll trunk'also terminates in the toll line circuit shown` to the right in Fig. 6.

'Having'given a general description 4of the system "and drawings, the detailed .circuit operations willnowbe explained.

For this purpose it will be assumed that one fof the regular magneto subscribers wishes to be 'connected 'to another Vlocal station. The calling subscriberoperates the hand generator at his telephone inthe -usual manner, projecting ringing :current over his line conductor and through the upper winding of line relay II. This ringing'current `passing through the upperwinding of `line relay II causes the .energization of relay II which therefore at armature I3 connects negativel battery through the windingv ofY cut-onrelay: I2 tothe' third bank contact accessible tothe finder wiperl. At armature I4 relayII closes a circuit extending through the lower vwinding of line relay I I, armature I8, finder start conductor l'130, and through the winding of startV relay 20| to ground. Line relayv II immediately locks itseltoverthis circuit and .start relay v20| ener- "gizes At armature I5 line relay II opens a point in its original energizing circuit. Start relay 20 I, upon'energizing, at armature 2I2 completes an `obvious circuit for energizing'slow to operate relay 202gand at'armaturev 2I3 completes a circuit 'for' energizing relay 203 afterthe distributor has fpreselectedanidle trunk in the connector link.

Relay 202 lenergizes after'v an interval and at armature 2I5 completes a short` circuit around its winding' to cause this relay to Adeenergizeafter anV interval. Relay 202 therefore intermittently leriergi'zes'and deenergizes and at armature 2I4 connects and disconnects ground from conductor 210 'to generate artone Ain the control trunk which if in use on another call will inform the control operator that another call'has been initiated by another subscriber. The circuit'for Yenergizing relay'203 may be traced as follows: from ground `by`way of conductors262, armature lr232 and resting contact, 'conductor 213,'armature v330, Vconductor28|,iarrnature 231 andvworkingV contact, armature 245, armature 2 I3, through the windingrof 'relay-'203.' interrupter springs 245 of springs .|24 of y'the busy keys in all of the idleV local connectors thru the off normal springs I22 `of Ltheidle connectors, armature II'I, by way of the commoncha'in conductor 69 and through the winding of relay 208 to battery. It should possibly v-b'ementioned at this time that conductors 260, 26I and 262 may, if desired, extend to a relay'group such as the relay group shown in Fig. 5 in the above'mentioned application,fforfenabling an voperators `control 'trunk to 'be switched Cfrom one R-.C. X.fto'a second'simil'ar R.'C.-X.

vRelay v203, upon energizing over the fabove traced circuit, at armature 2I9 vmaintains alllink-'busy relay 208 vin energized position, :at vvarmature 220 completes a circuit for energizing motor magnet 6'4 Vof :the'preselectediidle finder-'connector link, at farmature'ZZI opens the stepping circuit tomotor magnet Y251! and prepares a point in the circuit to relay Il'3and relay IM inthe local connector, at armature i222 completes cir-.- cuits for relays 2IIz and-'205, and at armature 223 closes the test circuit through the winding of re-V lays200 and 201.

Relay 205 energizes-b'y way of armature 2I8 'beforefthe .slow to operate .relay 2I'I is fully energized `and operates its vweighted armature *226 to close springs 2286 and 288, thereby completing an obvious circuit for 'slow to release Vrelay204. At1farmature=225, relay 204 completes fa'locking circuitforitself independent of springs -288 'and at armatureZIBfopens a point in a circuit extending to motor magnet 253 "before slownt'o'operate relay 2 I'I closes its armature 224.

-Slow-.to-'operate v relay 2I'I, Aupon energizing, l 'at armature224 preparesI a circuit for motor mag- Inet 253ffandfat armature 2I8 opens the circuit of relay-205. `YRelay'2Il5"releases its weightedarmature 1226 which' now Vvi-brates between "springs 28I rand -288 to 'hold thev slow-to-'relea-se relays 204 -inenergized position for a predetermined time. This predetermined time is approximately four isecondsorsuioient time to associate the -calling lineto I an'idle '-finder-connectorlink.

The circuit for energizing the motor 'magnet '6410i thepreselected findereoo'nnector linkfmay 'be traced as follows: from ground by 'way of armature 220,armature'228iand`resting Contact,

armature 22'I., lWiper 'e251 ein wengagement -with the fbank contact Lterminating 'the preselected link, conductor 61;l and through `the winding of motor vmagnet-(i4 to battery. Motorv magnet-64, upon fenergiz'ing, positions its pawlf-preparatory to stepping tthe "wipers-of the finder `andv atarf mature B3 grounds '-conductor'f `to complete-a circuit; forthe Isteppingy relay 206` in the v.distri- Avbutor. This circuitl Ymay be traced from'grounded conductor 'byj'wayfoffthe 'distributor bank contact and v"wi-per-256-and throughtheV upper vw'indingof'stepping relay 206 to battery. At ar-V mature -22'I relay 2206,- upon energizing, opens the circuit v to motori-magnet 64' which thereupon deenergizes. -Motor-tmagnet'l64, n-upon deenergizing, advances the Wipers `of the-tinder'one step and at armature 63 opens the circuit to stepping relay 206. Stepping relay 206 deenergizes and at armature 22'! recloses the circuit to motor magnet 64. This interaction between magnet 64 and stepping relay 266 continues until the test wiper 6I of the nder encounters the marked calling potential applied tc the bank contact of the calling line.

When wiper 6| of the nder encounters the marked calling potential relays 206, 207 and |2 are energized in series over the following circuit: from ground by way of conductor 260, armature 223, through the lower winding of stepping relay 206, through the upper winding of test relay 201, wiper 258, conductor 68, wiper 6| in engagement with its third bank contact, conductor 24, armature |3 and through the winding of cut-oir relay 2 to battery. Stepping relay 206 is maintained energized over this circuit to open the circuit to motor magnet 64, at armature 227. Cut-off relay I2, upon energizing, at armature I6 opens the original energizing circuit of line relay at armature connects its Winding to conductor 24 independent of armature |3, and at armature I8 opens the circuit to start relay and the locking circuit extending through the lower winding of line relay Line relay thereupon deenergizes and at armature |5 prepares a point in the talking circuit to the calling line.

Test relay 20|, upon energizing, at armature 220 opens a further point in the stepping circuit to magnet 64, and completes a circuit through its working contact from grounded armature 220 for energizing motor magnet 253. At armature 230 test relay 201 grounds conductor 65 to 'complete an energizing circuit for relays |03 and |04 in the local connector. At armature 23| completes a locking circuit through its lower Winding to grounded conductor 264, at armature 232 opens the circuit to relays 203 and at the working contact and armature 232 completes a circuit for energizing relay 436. Start relay 20| deenergizes when its circuit is opened by relay 2 and at armature 2|2 opens the circuit to relay 202, which now deenergizes. At armature 2|3 relay 20| opes a further point in the circuit to relay 203. Motor magnet 253 energizes in response to the operation of test relay 201 and positions its pawl preparatory to stepping the wipers of the distributor. At interrupter springs 254 motor magnet 253 opens a further point in the circuit of relay 203.

Relays |03 and |04 in the local connector are energized over the following circuit: from ground by Way of armature 230, working contact and armature 22|, wiper 255, conductor 65, springs |23 of the busy key, oil normal spring |25 and resting contact, through the winding of relay |03 to battery and by way of the nor-l mally closed springs controlled by armature |40 through the winding of relay |04 to battery. At armatures ||5 and ||9 relay |03 prepares points in the talking circuit to the calling line, at armature disconnects one of the multiple groundsfrom the chain conductor 69, at armature H8 completes a locking circuit for itself from grounded armature ||2, armature ||6 connects ground at armature |55, to the connector hold conductor 68 to hold the cut-01T relay l2 in the calling line circuit in energized position. At armature |20 relay |03 opens a point in the circuit of the release magnet |09, Connector relay |04, upon energizing, at armatures |21 and |3'| connects the calling line to the talking conductors 268 and 269 in the common equipment, at armature |28 connects the negative ring conductor |81 to the Wiper |'5|, at armature |36 connects the positive ring conductor |88 to wiper |54, at armature |29 connects ground to Wiper |52, at armature |30 prepares a circuit for vertical magnet at armature |3| prepares 'a circuit for the cut-through relay |05, at armature |34 prepares a circuit for rotary magnet l0, at armature |35 prepares a circuit for release relay |02, and at armature |32 prepares the circuit for relay |06.

Relay 203 deenergizes after an interval and at armature 2|9 removes one of the ground connections from conductor 69. At armature 220 relay 203 opens the circuit to moto-r magnet 253 to deenergize the same. At armature 22| closes the preselecting searching circuit to enable the distributor to preselect an idle link, at armature 222 opens the circuit of relay 2H, and at armature 223 opens a point in the test circuit. Motor magnet 253, upon deenergizing, steps the distributo-r wipers 255 to 258, inclusive, one step and closes its interrupter springs 254 to complete the preselecting circuit by means of which the distributor preselects an idle link. In case wiper Z is in engagement with a bank contact terminating the guard conductor of a busy link then such conductor is grounded with the result that a self interrupting circuit is completed for motor magnet 253 as follows: from grounded bank contact engaged by wiper 255, armature 22| and resting Contact, interrupter springs 254, and through the winding of magnet 253 to battery. Motor magnet 253 operates in the same manner as a buzzer as long as wiper 255 engages grounded bank contacts and stops when wiper 255 no longer encounters a grounded bank contact. Since all of the busy links have their guard conductors, such as conductor 65, grounded then the motor magnet 253 will continue to step the wipers of the distributor until such time as wiper 255 stops on a bank contact terminating a nongrounded conductor 65. Relay 2| deenergizes after an interval, and at armature 2|8 prepares a circuit to relay 205. Relay 204 likewise deenergizes after an interval after the Weighted arm 226 stops vibrating between springs 286 and 288.

At this time it may be advisable to describe the function of the slow releasing device when, due to some fault, a finder does not switch through and connect the calling line. In this Case test relay 20|, due to a fault, does not energize, and after a predetermined time relay 204 deenergizes and at armature 2|6 energizes motor magnet 253 by Way of armature 224. Motor mag` net 253 at interrupter springs 254 opens the circuit to relay 203 which thereupon deenergizes. At armature 222 relay 203 opens the circuit to relay 2 which deenergizes and at armature 224 opens the circuit to motor magnet 253 to cause the wipers to search for another idle iinder connector link.

Relay 430 energizes in response to the operation of test relay 207 over the following circuit: from grounded conductor 262, armature 232 and working contact, armature 252, conductor 263, normally closed springs controlled by armature 431, and through the winding of relay 430 to battery. At armature 432 relay 430 opens the loop circuit extending over the control trunk conductors 35| and 452 to the remote operating center and at armature 433 completes the circuit for energizing the slow-to-operate relay 43| as follows: :from ground .by way of yarmature 433, conductor 293|, .armature :289, conductor 290, and ithrough the winding of relay :432| to battery. Alt `armature 434 relay 43| `prepares a point in the circuitfof relay 5303, Vat armature '439 closes a circuit to the :local lemergency operating set, :at armatures 435 and 436 .disconnects the supervisory switch, at l.armature 438 locks itself fto grounded yconductor 264 by way of vconductors 29| and V290, at armature 431 opens the circuit to slow-to- -release relay 430, and at armature 44| prepares a point in the circuit Afor short Acircu'iting the righthand winding of the .repeating coilRC'I in Athe `conn-non equipment.

Relay 41.0 at vthe remote operating center -is normally .energized over the control trunk as :follows: lfrom ground through theV lower windings of relays -302 and 130|, conductor l215|, lower lett-'hand winding .of repeating coil RC4, conductor 452, lower right-hand Winding of repeat- .coil RC2, upper low resistance winding 4of relay 410, 'through the lower high resistance 'Winding of relay `41|), resistance R, Working con- 'tact and armature 312, normally closed springs `controlled by `key springs V462, upper right-hand winding of repeating coil RC2, trunk conductor Y 45|, :armature 432, upper left-hand winding of :repeating coil RCL conductor 210, Land through .the upper windings of relays 30| and 302 in series Yto' battery. Due Sto the inclusion of lthe resistance 'R 1and the high resistance winding or `relay 410 line relay 302 in the common equipment is not energized. In :addition relay 530| being a differential relay likewise does not energize over this circuit. Relay 410 `'in the remote operating center deenergizes when relay 43|! Vfat armature 432 opens the previously traced circuit therefor.V

`Atarmature 412 relay 4110 interrupts its vown lcircuit and substitutes 'relay 41| which 4thereupon :energizes over :the control trunk when relay -430 deenergizes, which it does an interval after relay 43| opens its circuit at armature 4'3-1. Relay 430, -upon deenerg-izing, lat armature-432 completes `the :circuitover the control trunk Afor energizing-relay -4T||by way of armature 412 and its resting contact. VAt armature 41-5 relay 41| completes the circuit 'for lighting the lamp v4.14V to signal the operator at the remote loperati-ng center. addition, in case the night alarm keyrNA Tis closed .as shown in the drawing, then fthe -deenergization of relay -41'0 at .armature .413 con-1- pletes a circuit forzoperating thebuzzer over 'an obvious circuit 'to .sound an `alarm and thereby attract Vthe .operators attention.

'In response to the operation of the signal fill-4 lthe .control operator :operates the key K to throw her head-set across theterminals lof the left-hand 4windings of repeating :coil RC2 by'wayoisprings 415|! and 464. The -operationof Ikey K also fopen's the :circuit :of relay 443| at Ithe normally closed 'springs controlled 4by springs J4162 and in :addition substitutes lthe vupper low resistance winding -of 'relay 41D for relay 411|. Relay 410 .is now energized from ground and battery through the Windings of line relay 3D2 in the #common `equipment over the Vpreviously traced :circuit through the right-hand windings `of repeating ,coil RC2 .land .thence by way of the :upper winding fof relay 410, fsprings 45|, impulse-springs 469 of the-calling .deviCe'CD, 'spring 48'2 .and working contact. At .armature 41.2 relay 41|! opens a .further point in :the circuit of relay `:41| and 'at its working com :tactprepares ra :circuit :for including .the .resistance Rand the high resistance lower windingin series with :the control :trunk when the .keyKis released.

acta-'vso At armature -413 relay 4123 opens -the buzzer foircuit.

Vflln -case a .pay-station telephone originates a f Y call-'a relay ftone :group v(n'o't shown) is started in operation and connects pay-station tone to contion tone is connected :directly to the controlV trunk by fwaylof `conductor221|) instead lof to Ythe pay-station line conductor. Y

If another local R. 5C. X. vsubscribershould initiate -a call at ithis time, .start .relay I21H and relay 2in-2 will operate the same manner as previously -"described,1and in this -case the intermittent Yoperation :of relay 202 connects ground by way of Iarmature 214 and the resistanceto `conductor `21D to Inotify the operator that -a second call israw-aiting her attention. In 'the present' application waiting tone is Aput -von immediately .in response to the initiation of a call.

When the -low resistance upper Winding :of relay 41|] in the 4renlo'te operating center 4is bridged 'across fthe trunk conductors y45| and 452 -by the loperation fof key K, line relay -302 is energized thereover `byWa-y sof conductors i210 and 21| over the previously Itraced circuit. At armature 3|1 relay 392 disconnects ground from conductor 211 `and -at armature 3158 completes al circuit for energizing slow-lto-release 'relay 305. At armature pletes acircuit for energizing slow-to-release re- -lay 306. A-t armature 323 relay 315 prepares a 'point in the impuls-ing circuit and at armature through and lrelease circui-ts, at armature 321 'as the result of asubscriber initiating a call, andV in response to Ythe control operator `operating her dial 'and answer key K. The operator -now answers fthe ycall and receives Athe number jof the line -to be called. The talking circuit between the Icalling lsubscriber and the control operator may be traced 'as follows: from the calling line over line conductors `22 and 23, wipers 60 `and 62, vconductors 12 and 18, armatures ||5 and H0, anna- 'tures |'43 and |41 and their resti-ng contacts, Iarmatures 121and 131, conductors |-85' andV |86, resting 'contacts and armatures '329 and 33 conductors 268 and '269, repeating coil RC-|, c'onductors I45| and 452, repeating coil RCV-2, key springs '468 land 464, to the opera-tors telephone circuit. After receiving the number o'f the desired called subscriber the operator will Aoperate 'the calling -device'CD in accordance with the iirst 'digit Ici the lcal-led number. Since springs 465 to 438,-i-nclusive, operate-and close on the rst movement of the ycalling'device and remainy in operated condition until the calling ydevice reaches itsnormal position. The springs '465 and "4B-6 close a lshunt circuit around the lower Aleft-hand Winding Yof repeating coil RC2 fand lshunt springs v461 and '446 complete a shunt circuit laround the upper winding-of relay 410 5to improve the impulsing circuit. This shunt gcircuit may be traced from the left-hand terminal of the upper winding fof vrelay 419 through springs 43|, shunt springs 468 and d3?, key springs 433, to the right-hand terminal of relay M9. The impulse springs |39 of the calling device are now connected in bridge of the trunk as follows: through key springs 462, impulse springs 339, shunt springs 438 and 457, and key springs In response to the operation of the impulse springs 399 the circuit extending over the control trunk to relays 33E and 392 is opened for each irnpulse of the digit dialled. Line relay 332 deenergizes for each impulse and at armature 3I3 completes the impulsing circuit to the series relay 3| and the vertical magnet I I I in multiple as follows: from ground by Way of armature 3|3 and resting contact, armature 323, armature 348, where the circuit divides, one branch extending through the winding of slow-to-release series relay 3| I to battery, and the other branch extending by way of armature 353 and resting contact, conductor |93, armature |39 and through the winding of vertical magnet to battery. Relay 3| I, being slow to release, is maintained energized throughout the impulsing period and at armature 349 short circuits the right-hand winding of repeating coil RCI by way of conductor 293 and armature 44|. At armature 353 relay 3i I disconnects ground from conductor |99 and at the working contact of armature 35E! completes a circuit for energizing relay 3I2 by way of armature 352 and resting contact. At armature 35| relay 3|2 completes a short circuit around relay 3|3 as follows: from ground by way of armature 359 and working contact, armature 352 and resting contact, through the winding of relay 3|3, armature 35| to the grounded lock conductor 399.

Vertical magnet II! raises the wipers I5I to |54, inclusive, one step for each impulse received, thereby stepping the wipers of the local connector opposite the level of bank contacts terminating the called line. On the iirst vertical step of the Wipers Vertical off-normal springs |25 grounds the guard conductor 65 and opens the original energizing circuit of relays |33 and |34 now held energized from armature I I2. Vertical off-normal springs |22 operate on the rst vertical step of the Wipers to open a further point in the circuit for grounding the chain conductor 69. Vertical oifnormal springs I2| also operate on the rst Vertical step of the switch wipers to open the circuit to the release magnet |99.

After the impulsing period slow-to-release series relay 3H deenergizes and at armature 353 opens the short circuit around the winding of the relay 3|3 with the result that relay 3|3 energizes in series with relay 3|2 from grounded lock conductor 399. At armature 352 relay 3|3 opens the original energizing circuit of relay 3|2 now held energized in series with relay 3 i 3 and at its working contact prepares the circuit for relay 3 I4. At armature 353 relay 3I3 transfers the impulsing circuit from the Vertical magnet I I I to the rotary magnet I I3 and at armature 353 prepares a point in a circuit to the supervisory motor magnet 49| In response to the second series of impulses dialled line relay 392 again deenergizes for each impulse and upon each deenergization transmits an impulse to the series relay 3| I over the previously traced circuit and also to the rotary magnet as follows: from ground by way of armature 3 i3 and resting contact, armature 323, armature 343, armature 353 and working contact, terminal 9, the dotted line connecting terminal 9 to terminal I9,

I conductor |95, armature |39 and rotary magnet III] to battery. The rotary magnet IIB rotates the wipers of the local connector to the bank contacts terminating the called line. Series relay 3II again energizes during the impulsing period and' at armature 350 disconnects ground from conductor |89 and wiper I 52 during the rotary movement and at the working contact of armature 359 completes a circuit for energizing reiay'3Il as follows: from ground by way of armature 359 and working contact, armature 352v and working contact, armature 35?, and through the winding of relay 3M to battery. At armature 355 relay 3M closes a short circuit around the winding of relay 3| 5 from grounded lock conductor 339 and grounded armature 359. After the impulsing period series relay 3| I deenergizes and at armature 339 removes the short circuit from around the repeating coil RCI. At armatureY 350 relay 3M grounds conductor |89 to complete a circuit for energizing the cut-01T relay, such as cut-off relay i2, of the called line and at its working contact removes the short circuit from around relay 3I5 to allow relay 3|5 to energize in series with relay 3M, 'Ihe circuit for energizing relay 3|5 extends from grounded lock conductor 399 through armature 355 and working Contact, and through the winding of relays 3 I 5 and 3 I 4 in series to battery. At armature 351 relay 3|5 opens points in theoriginal circuit of relay 3M and at armature 358 completes the circuit for energizing the monitoring relay 301 as follows: from ground by way of armature 359, armature 320 and through the winding of relay 391 to battery. The circuit'for energizing the cut-off relay of the called line may be traced as follows: from ground by way ofv armature 359 and resting contact, conductor |89, armature |29, wiper |52, the test bank Contact of the called line and through the winding of the cut-oit relay similar to cut-off relay I2 to battery. The cut-off relay of the called line, upon energizing at its upper armature, corresponding to armature I6, opens the circuit to the line relay, at its lower armature, corresponding t armature I 8, opens a point in the start circuit, and at its middle armature, corresponding to armature grounds the corresponding nder connector bank to make the called line busy to the nder switches.

Monitor relay 3M, upon energizing, at armatures 329 and 33| disconnects the talking conductors extending to the calling line from conductors 263 and 239 and connects the talking conductors 238 and 239 to the negative and positive ring conductors |31 and |33 to provide a listening circuit over which the control operator can determine if the called line is idle or busy. The control operator is now connected in a talking circuit with the called line over the circuit extending from the contacts of the called line, wip-ers I5I and |54, armatures |28 and |36, nega- .tive and positive ring conductors |87 and |88,

working contacts and armatures 329 and 33|, conductors 238 and 239, through the right-hand winding of repeating coil RCI. The voice currents are induced through the left-hand Windings of repeating coil RCI over trunk conductors 45| and 552 to the right-hand windings of the repeating coil RC2 in the remote operating center from where the voice currents are repeated through the left-hand windings of repeating' coil RC2 through the key springs S39 and 484 to the operator telephone circuit. If the called line is busy and is one of a group of lines having the same called number, the operator dials the digit l causing the rotary magnet Il!) to advance the wipers of the connector to the next line and again listens. The operator continues to Idial the digit 1 until an idle line or the last line in the group is reached. In case'the operator does not hear any conversation she will then challenge to determine if the line is in use. If the operator receives no response she will then lcode ring o the desired called subscriber.

In case the line is busy the operator will mo- K relay 30| may be traced as follows: from ground by Way of the monitor springs, key springs 463, lower right-hand Winding of repeating coil RC2, conductor 452, lower left-hand winding of repeating coil RCI, conductor 21|, through the lower winding of differential relay and through the lower Winding of line relay 302 to ground. Line relay 302 is held energized over its upper winding and differential relay V30 upon energizing, at armature 3|6 grounds conductor 215 to complete a circuit for energizing relay i303 by Way of armature 434 and working contact, conductor 214, armature 32| and resting contact, and through the winding of relay 303 to battery. At armature 3|9 relay 303 short circuits relay 304 from ground extending by way of armature 3|6 over the previouslytraced circuit to armature 32| and resting contact, through the winding iof relay 304 and armature 3|9 to groundedlock conductor 390. Upon restoration of the two-Way key to its normal position the short circuit around the lower Winding of differential relay 30| is removed with the result that differential relay 30| now deenergizes. At armature 3|6 relay 30| disconnects ground from conductors 215 and 214 to remove the short circuitrfrom around relay 304 whereupon the latter relay now energizes in series with relay 303 from grounded lock conductor 290. At armature 32| relay 304 opens the original energizing circuit of relay 303 and at its working contact prepares the circuit for ringing relay 308, and at armature 320 opens the circuit of Ymoniter relay 301. Relay 301 deenergizes and at armatures 329 and 33| reconnects the talking conductors 268 and 268 associated with the control trunk to the talking conductors of the calling line. The control operator now informs the calling party that the called line is busy.

In case the called line isY idle the control operator operates the key to monitor position with the result that relays 30|, 303,V 304 and 301 operate as just described..V The control operator now operates the two-way key to ringing position in accordance with the code ring of the called subscriber. Differential relay 30| is operated once for each key operation to ringingrposition and grounds the conductors 210 and 21| of the control trunk previously described. Upon each energization of differential relay 30| that relay at armature 3|6 grounds conductors 215 and 214 by way of armature 434 from whence the circuit extendsby Way of armature 32| `and working contact, terminal 6, dotted linie, terminal 5, and through the windings of ringing relay 308 and relay 3D0-in multiple to battery. Ringing relay 308 is energized each time the key is operated to ringfposition while'the slow to release relay 308 is operated during the ringing period. Each time ringing relay 308 is energized ringing circuit for ringing the called subscriber is completed at' armatures 338`and 34| as follows: from the generator lead by way of conductor 15, working contact and armature 338, terminal dotted line, terminal 2, conductor |81, armature |28, wiper |5| in engagement with the bank contact of the called line over the called subscribers line through the wringer, over the positive line conductor, to Wipers |54, armature |36, conductor |88, terminal 3, dotted line, terminal 4, armature 34| and working contact, to generator return conductor 16. At armature 335 ringing relay 308 prepares a circuit for relay |06 used in reverting and toll calls, at armature 333 completes an obvious circuit for energizing relay 3|0, and at armatures 336 and 339 completes the ring-back tone circuit for both the calling subscriber and the control operator. The ring-back tone circuit for the control operator extends from generator lead, conductor 15, tone condenser C, armature 336, to conductor 268, and thence over the previously traced circuit through the repeating coil RCI back to conductor 269, and from thence by Way of armature 339, tone condenser C to generator return conductor. The ring-back tone to the calling subscriber may be traced from the tone condenser C, armature V336 and resting contact, conductor |85, armature |21, armature |43, armature ||5, through the previously traced loop of the calling line to conductor 13, armature ||9, armature |41 and resting contact, armature |31, conductor |86, armature 33|, armature 336to the tone condenser C.

If, in a previous connection, another connector is in engagement with the bank contacts of the called line, because of failure of the subscriber to ring oif that connection, then the first pulse of generator applied to the called line causes the energization of the A. C. relay |01 in this other connector to cause its release. The circuit for energizing relay |01 in this connector may be traced from the negative bank contacts of the called line and thence by way of wiper |5|, ar-

matures |44 and |38, the upper left-hand winding of repeating coil RC, through the winding of relay |01the lower left-hand winding of repeating coil RC, armature |46, wiper |54, and positive bank contact of the called line. Relay |01 of the non-released connector at armature |48 completes the circuit for energizing release relay |02 which causes the release of this other connector in a manner to be described more fully hereinafter.

Relay 309, due to its slow to release characteristics, is maintained energized during the ringing period and at armature 343 connects ground through both the left-hand windings of repeating coil RC3 to connect ground to the negative and positive ring conductors |81 and |88 at the time ringing relay 308 is in deenergized position in order to discharge the ringing condensers associated with the called line. At armature 342 relay 309 disconnects the-right-hand Winding of repeating coil RC3. Relay 3|0, upon energizing, at armature 345 prepares a point in the three-way talking circuit between the calling subscriber, the called subscriber, and the control operator, at armature 346 prepares a point in the talking circuit and for enabling ground at armature 343 to discharge the ringing condensers associated with the called line, at armature-335 preparesY a point in the circuit to the cut-through relay |05, at armature 341 completes a locking circuit for itself from grounded armature 321, and at armature 348 opens a point in the impulsing circuit.

Each operation of the two-way key to ringing position therefore causes the energization of differential relay 30| and ringing relay 308 to ring the called subscriber in accordance with his code. An interval after the ringing period relay 309 deenergizes and at armature 342 completes a threeway talking circuit between both subscribers and the control operator as follows: The talking circuit between the calling subscriber and the control operator is the same as previously traced. A branch of this circuit extends from conductors 258 and 253 through the right-hand windings of the repeating coil RC3. Voice currents are induced into the left-hand windings of repeating coil RC3 and thence by way of the heavy talking conductors, armatures 338 and 34|, conductors |81 and |30, armatures |28 and |36, wipers I5| and I 54, and over the line conductors of the called line to the substation circuit.

The control operator either waits until the called subscriber answers or may disconnect from the control trunk and release the common equipment without waiting for the called subscriber to answer. Assuming that the control operator waits until the called subscriber answers, then when the operator is satisfied that the desired party has responded she will restore the key K to cause the release of the common equipment which in so doing establishes a new talking circuit between the calling and called subscribers. In response to the restoration of the key K, springs 460 and 434 disconnect the operators telephone circuit and springs 432 and 463 reconnect both windings of relay 410 and the resistance R in bridge of the conductors 210 and 21| to cause the deenergization of line relay 302. Line relay 302, upon deenergizing, at armature 3|8 opens the circuit to slow release relay 305. Relay 305 deenergizes after an interval and at the working contacts of armature 322 disconnects ground from conductor 218 and opens the circuit of relay 306 and at its resting contact momentarily grounds the cut-through conductor IBI to cause the energization of relay |05. At armature 325 relay 305 disconnects ground from conductor 264 to deenergize test relay 201 and relay 43|. Relay 201, upon deenergizing, at armature 228 prepares the circuit for motor magnet 34, at armature 23| opens a further point in its own locking circuit, and at armature 232 grounds conductor 213 to prepare the circuit for relay 203. Relay 43|, upon deenergizing, at armature 434 disconnects conductors 214 and 215, at armature 44| disconnects conductors 266 and 268, at armatures 435 and 435 reconnects the supervisory switch to conductors 268 and 269, at armature 438 opens a point in its own locking circuit, and at armature 431 prepares a point in the circuit to relay 430.

The circuit for energizing cut-through relay |05 in response to the deenergization of relay 305 may be traced as follows: from ground by way of armature 322 and resting contact, armature 325, armature 355 and working contact, cut-through conductor ISI, armature |3| and through the Y winding of cut-through relay |05 to battery. At

armatures |33 and |42 relay |05 connects the right-hand windings of repeating coil RC to the calling line, at armature I 3B connects the lefthand vwindings of repeating coil RC to the called line, at armature |39 grounds wiper |52 to maintain the cut-off relay I2 of the called line in energized position, at armature |40 completes a locking circuit for itself from grounded armature ||2, and also opens the circuit of relay |04 which deenergizes, at armature |4| prepares a circuit for relay |02, at armature |55 disconnects direct' ground from conductor 68 and substitutes ground through the winding of marginal relay |10 for holding the cut-off relay I2 of the calling line in operated position, and at Aarmature |45 prepares a circuit used in toll connections. Relay |04, upon deenergizing, at its armatures disconnects the common equipment from the local connection. The calling and called subscribers are now connected over the following talking circuit: from the calling line over the previously traced heavy talking conductors to armatures ||5 and IIS, and thence by Way of armatures |43 and |41 and their resting contacts, armatures |33 and |42, to the righthand winding of repeating coil RC. The called subscriber is connected over the talking conductors of his line to wipers |5| and 654 and thence by Way of armatures |44, |38 and I 43 through the left-hand windings of repeating coil RC. Voice currents are induced through the windings of the repeating coil RC thereby enabling the calling and called subscribers to converse with each other.

Slow-to-release relay 333 deenergizes an interval after its circuit is opened by the deenergization of relay 305, and at armature 325 opens the original energizing circuit of cut-through relay |05, which is now locked in energized position. At armature 321 relay 306 disconnects ground from the tone start lead and from the lock conductor 390 to cause the deenergization of relays 303, 304, 3|0, 3|2, 3|3, 354, and 3|5. At armature 328 relay 306 disconnects ground from the ringing machine start lead RMST and grounds conductor 254. At armature 330 relay 306 prepares a circuit for relay 203, and at armature 332 grounds conductor 211 and wiper 403 of the supervisory switch. The common equipment is now released and may be used on another call.

After conversation and in response to the calling subscriber ringing oif, relay |08 is energized over the previously traced talking circuit to the calling line. If the called subscriber rings 01T relay |01 is energized over the previously traced talking circuit to the called line. In response to the energization of either relay I3? or |08 the circuit for energizing relay |02 is completed `at armature |40 or |49, from ground at armature |4I. Relay I 02, upon energizing, at armature ||3 connects a multiple ground to relays |03 and |05 to hold the same energizedand at armature 4 grounds conductor 14 and completes an obvious circuit for energizing relay Relay |0I at armature I|2 disconnects one of the multiple grounds holding relays |03 and |05 inrenergized position. After ringing oil relays |01 and |08 deenergize and open the circuit of relay |02. Relay |02, upon decnergizing, at armature ||3 opens the circuit of relay |05 and |03 which now deenergizes and at armature ||4 opens the circuit to sloW-to-release relay 0| which deenergizes after an interval. Relay |05, upon deenergizing, at armatures |33 and |42 disconnect the right-hand windings of the repeating coil RC, at armature |33 disconnects the left-hand windings of repeating coil RC, at armature |30 disconnects ground from wiper |52 to deenergize the cut-01T relay I2 of the called line, at armature |40 opens a point in its own locking circuit and prepares the circuit for-relay |04, and at armature I4I opens the circuit of relay |02. Relay !03, upon deenergizing, at armatures ||5 and I9 opens the circuit to the calling line, at armadeenergizes after relays |03 and |05 have com-Y pletely deenergized. In response to the operation of the release magnet |09 the switch wipers are restored to their normal positions in the well known manner. Off-normal springs |2| open in response to the wipers reaching their normal position to open the circuit to release magnetr |09. In response to the restoration of off-normal springs |25 ground is removed from guard-lead 65 to make this local connector switch selectable and to prepare circuits to relays |03 and |04. The restoration of off-normal springs |22 grounds thechain start conductor 60 to maintain the all link busy relay 208 in energized position. In the calling line circuit the cut-off relay |2 deenergizes; at armature I6 reconnects the line relay and at amature I8 reconnects the start conductor 30. In the called line circuit the cut-off relay deenergizes and reconnects the line relay and start conductor in a similar manner. The entire connectionY is now released and may be used for another call.

In case the control operator found the called line busy the control operator would operate her two-way key to its monitor position to disconnect from the called line and connect the control trunk to the calling line. In'response to the operation of the key to monitor position the control trunk conductors 45| and 452 are grounded with the result that diierential relay 30| energizes as before. At armature 3|6 relay 30| again-completes the circuit for energizing relay 303 and the latter relay at armature 3|9 prepares the circuit for relay 304. The key is now released from its operated monitor position to its normal position, thereby causing the deenergization of differential relay 30 Relay 30 upon deenergizing, at armature 3|6 removes the short circuit from around relay 304 to allow the latter relay to energize in series with relay 303. At armature 320 relay 304 opens the circuit of monitor relay 301 to cause the latter relay to deenergize. Relay 301, upon deenergizing, at armatures 329 and 33| reconnects the control trunk to the calling line; The control operator now informs the calling subscriber that the line is busy and then restores the key K. In the same manner as previously described the restoration of the key K causes the deenergization'of relays 302 and 305. The deenergization of relay 305 at this time, since the ringing operation has been omitted, completes a circuit for energizing release relay 2 in the local connector as follows: from ground by way of armature 322 and resting contact, armature 325, armature 355 and resting contact, release conductor |96, armature |35 and through the winding oi relay |02 to battery. Relay |02 energizes and causes the release of the local connector in the same manner as previously described. In the Rcvertz'ng calls In making a reverting call the calling subscriber will initiate the call in the same manner as previously described. When the control operator answers in response to the signal and is informed that another subscriber on the same line is desired,the operator will inform the calling lsubscriber to replace hisreceiver. The control Voperator then operates the two-way key to monitor position and then to ringing position in accordance with the called subscribers code without dialling any digits. The iinder F, the distributor, and relays |03 and |04 in the local connector are energized in the same manner as previously described. The operation of the two-way key to monitor position grounds control trunk conductors 45| and 452 and conductors 210 and 21| to cause the energization of differential relay 30| as previously described. The operation of differential relay 30| at armature 3|6 completes the circuit by way of conductors 215 and 214 for energizing relay 303. When the key is released from its monitor position differential relay 30| deenergizes and removes the short circuit from around relay 304 whereupon thev latter relay now energizes in series with relay 303 as previously described. The operator now operates the twoway key to ringing position in accordance with the called subscribers code, thereby operating diierential relay 30| each time the key is operated to ringing position. Each time differential relay 30| is energized ringing relay 38 is correspondingly energized to ring back over the calling line. Relay 309 is energized in multiple with relay 308 and due to its slow to release characteristics is maintained in operated position during the ringing period, At armature 333 relay 308, upon first energizing, completes the circuit for relay 3|0 which accordingly energizes and locks to lock conductor 300. At armature 335 ringing relay 308, upon 'first energizing, completes a circuit for energizing relay |06 in the local connector as follows: from grounded lock conductor 390, armature 356 and resting contact, armature 335, conductor |92, armature |32 and through the winding of relay |06 to battery. At armatures 338 and 34| relay 308 completes the ringing circuit to the calling line as follows: from direct generator, conductor 15, working contact and armature 338, terminal the dotted line, terminal 2, conductor |81, armature |20, working contact and armature |43, armature ||5, conductor 12, wiper 60, conductor 22 over the calling line to conductor 23, wiper 62, conductor 13, armature ||9, armature |41 and working contact, armature |36, conductor |88, terminal 3, the dotted line, terminal 4, armature 34| and working contact, back to generator return lead 16. Relay |06, upon energizing, at

armatures |44 and |46 disconnects the left-hand windings of the repeating coil RC, and at arma.- tures |43 and |41 completes a point in the previously traced ringing circuit to the calling line. Relay 300, upon energizing, at armature 343 discharges the ringing condensers on the calling line during the silent period when ringing relay 308 is in deenergized position. When the calling and called parties answer the operator releases the key K, whereupon relays 302 and 303 deenergize in the same manner as previously described. At armature 322 relay 305 completes the following circuit for cut-through relay in the local connector asV follows: from ground by way of armature 322 and resting contact, armature 325, armature 355 and working contact, conductor |9|, armature |3|, and through thewinding of relay |05 to battery. At armature 326 relay 305 opens the circuit t0 relays 201 and l43| to cause their deenergization and at armature 322-and work- Y ing contact opens the circuit Yto relay |05; Re-

Y RC from the calling line.

lay |05, upon energizing at armature |40 again completes its locking circuit and also opens the circuit of relay I 04 to deenergize the latter relay. At armatures |33 and I 42 relay |05 prepares circuits for connecting the right-hand winding of repeating coil RC to the calling line. Relay |04, upon deenergizing, disconnects the local connector from the common equipment, and at armature |32 opens the circuit to relay |06. Relay |96, upon deenergizing, at armatures |43 and I4? and resting contacts, connects the right-hand winding of the repeating coil RC to the calling line. In the common equipment relay 306 deenergizes after an interval and at armature 321 opens the circuit of relays 303, 304, 3|0 and |06.

After conversation and in response to either the calling or called subscriber ringing oi, relay I 08 is energized over the calling line, and at armature |49 completes the circuit from grounded armature |4| for energizing release relay |02. At armature ||4 relay |02 completes the circuit for energizing relay II and at armature I|3 closes a multiple ground circuit through all relays |03 and i05 in operated position. Relay IOI, upon energizing, at armature I I2 opens one of the multiple grounds to relays |03 and |05. After ringing off relay |98 deenergizesand at armature |49 opens the circuit to relay |02 which deenergizes.

t armature H3 relay |02 opens the circuits of relays |03 and |05 which accordingly now deenergize, and at armature I I4 opens the circuit of relay ||l| which likewise deenergizes after an interval. Relay |03, upon deenergizing at armatures |33 and |42 disconnects the repeating coil Relay I 03, upon deenergizing, at armature ||8 prevents the reapplication of ground to the guard leadV 65 which ground was removed therefrom in response to the deenergization of relay |02. At armature grounds the chain lead 69 to maintain relay 208l in operated position and at armature I I6 disconnects ground through the winding of marginal relay |70 from conductor 08 to deenergize the cut-ofi relay I2 of the calling line. Cut-off relay I2, upon deenergizing, reconnects the line relay and start conductor as previously described. Grounded magneto lines call and receive calls in the same manner as above described. The repeating coil RC3 in the common equipment permits a line having its negative conductor grounded to talkY to a line having its positive line conductor grounded, otherwise two such lines connected together through the common equipment would be short circuited to ground, and therefore unable to talk to each other until the control operator disconnects the common equipment from the connector.

Common battery subscribers lines can also be connected to this type of R. C. X. exchange by the use of a line adapter such as shown in Fig. l comprising relays 59 to 56, inclusive. When a common battery subscriber, such as indicated by S, removes his receiver, relay 50 is energized over the calling loop as follows: from ground by way of the lower winding of relay 50', resting contact and armature 56, armature 58 and resting contact, the calling substation loop, armature 55 and resting contact, armature 5l and resting contact, and through the upper winding of relay 50 to battery. At armatures 90 and 9| relay 50 disconnects the AC relays 53 and 54.at theresting contacts and at the working contacts thereof prepares points in the talking circuit. At armature 59 relay 50 completes an energizing circuit for slow to release relay 5|. At armature 93 relay 5| completes an energizing circuit for slow to operate relay 52, and at armatures 92 and 94 momentarily completes an energizing circuit through the upper winding of line relay 3| as follows: from ground by way of armature 92 and working contact, resting contact and armature 96, armature 36, upper winding of line relay 3|, armature 35, armature 9'| and resting contact, armature 94, and through the resistance 99 to battery.

Line relay 3|, upon energizing, at armature 33 connects the calling potential through the winding of cut-olii relay 32 to the finder bank, at armature 34 locks to start conductor 30 and causes the energization-of start vrelay 20|, and at armature 35 opens a point in its original energizing circuit after first locking up. Slow-to-operate relay 52 energizes after an interval, and at armatures 96 and 91 opens a point in the original energizing circuit of line relay 3|. The operation from this point on is the same as that described for a magneto line, the talking circuit extending over the heavy talking conductors of the line adapter as follows: armatures 90 and 9| and their working contacts, condensers C and C', resting contact and armatures 5`| and 56, armatures 55 and 58 and their resting contacts, and the calling line loop. The talking battery for the calling battery line is furnished through the windings of relay 50. After conversation and in response to the replacement of the receiver, relay 50 deenergizes and at armatures 90 and 9| opens the talking circuit.

At armature 59 relay 50 opens the circuit to slov'rV to release relay 5| which deenergizes after an interval. Relay 5|, at armature 93 opens the circuit to relay 52 which deenergizes after an inter? val since relay 52 is slow to release as well as slow to operate. At armatures 92 and 95 relay 5|, upon deenergizing before relay 52 deenergizes, momentarily connects ground and battery to the line conductors of the line circuit LC-I to cause the operation of the relays, such as relay |01 or |08, in the connector in use yto cause the release of such connector. VThe circuit for energizing the relay |08 in the connector may be traced as follows: from ground by way of armature 92 and resting contact, working contact and armature 96, over the heavy. talking conductor of the line circuit LCI to wiper 60 of the inder, conductor 72, armature II5, armature |43 and resting contact, armature I 33, through the upper right-hand winding of Yrepeating coil RC through the winding of relay |08, through the lower right-hand winding of repeating coil RC, armature |42, resting contact and armature |47, armature I I9, conductor '|3, wiper 62 in engagement with its fth bank contact, armature 35, armature 91 and working contact, armature 95, and ,resistance 98 to battery. In response to the operation of relay |09 the connector is released in the same manner as previously described.

In case a commonv battery line is being called the operation is the same as previously described. In case the ,called common batterysubscribers ringer is bridged across the ,line conductors or connected to the upper negative line conductor and ground then ringing current is applied to conductor 39 as previously described and extends by way of armature 90 and resting contact through the winding of A. C. relay 53 to ground. A. C. relay 53 is energized over thisV circuit and at armatures 51 and. 58 and resting contacts disconnects relay 50, thereby reducing the impedance .to improve the ringing circuit over the called line.y At armatures 5`| and ,58 and their.

working contacts A. C. relay 'extends the ringing circuit by way of armature 55 and through the substation ringers to ground at armature 58 'in case the ringers are bridged across the line or through the ringers to yground at the substations in case the ringers are connected to the negative line yconductor and ground at the substations. When the called subscriber answers the previously traced circuit is completed for venergizing relay 50 during the rst silent period when relay 53 is n plete the circuit for energizing the relay, such as relay |01, in the local connector to cause the release thereof by the momentary connection of ground-and battery to the; conductors 39 and 40. In case the ringer of the called subscriber is con-- nected to the bottom positive line conductor then ringing current is connected to conductor 4| in a manner-hereinafter Vdescribed for divided ringing. VIn this caserringing currentextends by way of armature 9| and resting contact and through the winding of A. C. relay 54-to ground to cause this lrelay to energize for each application of ringing current to conductor 4|. At amature 56 relay 54 completes a circuit extending by way of resting contact and armature 58 for ringing the ringers connected to positive line conductor and ground. During a. silent period and when the called subscriber answers relay 50 is energized over the called line to complete the talking circuit as previously described.

Toll calls In order-'tocoinplete a toll ycall to a subscriber in the R. C. X. thejtoll operator inserts a plug of a cord circuit into the jack J. In response to the insertion oi the plug into the jack J springs 52| complete a circuit forienergizing relay 503 as follows: from ground through the lower winding of relay 503, lower winding of differential relay 504, lower left-hand winding of repeating coil RC5, resting contact and amature 521, conductor 59|, lower right-hand winding of repeating coil RC4, jack 'springs 52|, upper right-hand winding of repeating coil RC4, conductor 590, armature 525 andresting contact, Vupper left-hand winding of repeating coil RC5, upperV winding of differential relay 504, and throughthe upper winding of line relay 503to battery. Line relay 504 energizes over the above traced circuit but differential relay 504 does not energize because its windings are equal and oppose each other. At armature 53| relay 503 completes an obvious circuit for energizing slow-to-release relay 502. At armature 528 relay 502 prepares a circuit for Vthe upper winding of relay 503, at armature 529 completes a circuit for energizing relays 506 and; 508, as follows: from ground by Way of armature 529 and working contact, A'normally closed springs controlled by armature T538, amature 5'45l and resting contact, and through the windings of relays 506 and 508 in multiple to battery. At armature 53.4 relay 506 short circuits the right-hand winding of repeating 'coil RC5 to prevent noises in the operators head-set. Relay 508, upon energizing, at armatures 54| an'd 542 complete the'.

circuit for energizing line relay 5| of the toll line circuit as follows: from ground by Way of resting contact `and. armature 531, working contact and armature 542, armature 563, upper winding of relay 5|I, armature 564, armature 54| and.

working contact, armature 536 and.V resting contact, and through resistance 535 to battery. At armature 543 relay 508 completes an obvious circuit for energizing the slow-to-operate relay 501.V Relay 5| I, upon. energizing at armature 56| connectsv call-ing4 potential through the windings of both relay 5019 and 5||2 to the finder banks by way of conductor |65. At armature 562 locks itself over the common start lead 30 and also energizes the start relay 20|, and at armature 563 opens a point in its original energizing circuit after its locking circuit has been completed. Slow-tooperate relay 501 energizes after an interval and at armatures 535 and 531 opens the original energizing circuit of line relay 5|| and connects generator to the contacts 58| and 582- to release any connector having its wipers in engagement with such contacts. Atamature 538 relay 501 completes a locking circuit for itself from grounded armature 529 and `also opens the circuits of relays 506 and 508i which deenergize after an interval. Relay' 508,Y upon deenergizing, at armatures 545| and 542 disconnects generator from conductors |6| and |64 and the bank contacts 58| and 582, and connects the right-hand winding of repeating -coil RC5 to conductors |6| and |64. Atarmature 543I relay 508 opens the origlnal energizing circuit of relay 501. Relay 506, upon deenergizing, at armature 534 removes the short circuit from around the right-hand winding of repeating coil RC5.. Y

The operation of the start relay 20| causes the nder to find the toll trunk in the same manner as previously described, whereupon relays 509 and 5|2 energize in series with relays 206 and 20'|l as follows: from grounded conductor 260, armature 223, lower winding of relay 206, upper winding of test relay 201, wiper 258, conductor 68, Wiper 6|, fourth bank contact, conductor |65, armature 56|-, vwhere the circuit divides, one branch extending to the cut-oi relay 5.|2 to battery and thev other branch extending by way of armature 544y and resting contact through the winding of relay 509 to battery. Relay 5|2, upon energizing, at armature 564 disconnects line relay 5| I, at armature 565maintains its own circuit and the circuit to relay 5.09 independent of arr-nature 56|, and at armature 566-. opens the start circuit to relays 20| and the locking circuit of relay5| l. Line relay 51| I. accordingly deenergizes andat armature 563 prepares a point in the talking circuit. Relay 509, `at armature 546, opens the circuit to relay 5|0 to prevent the toll line being called'. The control operator is signalled inthe same manner as; described for a local call and thereupon answerssuch call by operating the key K. A tal-king circuit between the toll operator andthe control operator may be traced as follows: fromfthe toll operators head-set and cord circuit, jack springs 522 and 523, repeating coil RC4, conductors 590y and 59|, armatures 525 and 521 and their restingv contacta, repeating coil RC5, resting contact'I and armatures54l and 542', armature 563,' conductors |'6| and |64, wipers 60 and 62 of the. nder G, assuming the finder F and the local connector `in Fig. 2 to be the finder connector link taken into use on this call, conductors 't2 and 1'3, armatures ||5 and ||9, armatures A|43 and |41 and their resting contacts,

' 460 and 464 to the control operators heat-set.

Upon response of the control operator the toll operator informs the control operator of the desired connection. The control operator now dials the digits of the called number and operates the associated local connector in the same manner as previously described. In response to dialling the digits of the called number relay 301 is energized to disconnect the calling toll line from the control trunk and connect the called line in place thereof toenable the control operator to determine if the called line is busy or idle. In case the called line is idle the control operator will rst operate the two-way key to monitor position to cause the energization of differential relay 30| and relay 303 as previously described.

In response to the restoratio-n of the key from monitor position differential relay 30| deenergizes and permits the energization of relay 304 in series with relay 303 as previously described. The operation of relay 304 causes the deenergization of relay 301, thereby again connecting the toll operator with the control operator. The control operator now operates the two-way key into ringing position in accordance with the code of the called subscriber. Each time the key is operated to ring position diierential relay 30| energizes and causes the energization of ringing relay 308 to signal the called subscriber in the manner previously described. When the called party answers the control operator disconnects from the connection by restoring the key K, thereby causing the deenergizaticn of relays 302 and 305 to energize cutthrough relay |05 in the local connector as previously described. When relay 05 at armature removes the short circuit from around relay |10 the latter relay now energizes over the following circuit: from ground by way of the winding of relay |10, armature H6, conductor 68, wiper 6|, conductor |65, armature 565, and in multiple through the windings of relay 5|2 and 509. Due to the increased battery potential through both windings of relays 509 and 5|2 marginal relay |10 energizes and transfers the control of the connection from the local subscriber to the toll operator. At armature |1| relay |10 completes a circuit for energizing relay |02 from grounded armature |4| and at armature |12 completes a circuit for energizing relay |06 from grounded armature 4|. Relay |05, upon energizing, at armatures |43, |44, |46 and |41 disconnects the repeating coil RC and connects the conductor "i2 and 13 direct to wipers |5| and |54, thereby completing a direct talking circuit between the toll operator and the called line independent of the repeating coil RC.

Relay |02, upon energizing, at armature ||3 holds relays |03 and |05 energized, and at armature ||4 completes the circuit for relay |0l. Relay |0 at armature |56, places a partial shunt including resistance |13 around the winding of relay 10, but does not cause its deenergization at this time. After conversation and in response to the called subscriber ringing oi, ringing current extends over wipers |5| and |54, working contacts and armatures |43 and |41, armatures H5 and H9, conductors 12 and 13, Wipers 60 and 62, conductors 5! and |60, armature 563, armatures 54| and 542 and resting contacts, the righthand winding of repeating coil RC5, and through thewinding of relay 505. Relay 505 energizes in response to ringing current and at armature 533 completes the circuit for energizing relay 50|. At armature 526 relay 50| completes a holding circuit through the upper winding of relay 503, and at armatures 525 and 521 and their working contacts connects generator and generator .retLun to toll conductors 590 and 59| and from' thence by induction through the repeating coil RC4 to the operators cord circuit to give the toll operator disconnect supervision in the well known manner.

YThe toll operator can rering the called subscriber by the operation of the ring key 524 which causes the energization of differential relay 504 since the lower winding of differential relay 504 is short circuited by the operation of key 524. This circuit may be traced as follows: from ground by way of springs 524, upper right-hand winding of repeating coil RC4, jack springs 52|, lower right-hand winding of repeating coil RC4, conductor 50|, armature 521 and resting contact, lower left-hand Winding of repeating coil RC5 through the lower winding of diierentialrelay 504 and through the lower winding of relay 503 to ground. This same ground extends over the upper talking conductor by way of key 524, conductor 590, armature 525, upper winding-of repeating coil and through the upper windings of relays 504 and 503 to maintain relay 503 in energized position. Since the lower winding of differential relay 504 is short circuited, relay 504 now energizes. At armature 532 relays 504 completes the circuit for energizing relays 500 and 508 in multiple. At armature 534 relay 506 again short circuits the repeating coil RC5 and relay 500, at armatures 54| and 542 connects direct generator and generator return to conductors |64 and |55 to rering the called subscriber. E'ach operation of key 524 therefore causes the ener-v gization of relay 504 and the energization of relay 508 to connect ringing current to the called line to rering the code of the called line.

Invresponse to the receipt of the disconnect signal, the toll operator removes the plug'from the jack J, thereby separating the jack springs 52| to open the circuit to relay 503. Relay 503, upon deenergizing, at armature 53| opens the circuit to relay 502 which deenergizes after an interval. At armature 529 and working contact relay 502 opens the circuit to relay 501 which accordingly deenergizes and at the resting contact of armature 529 momentarily operates relay 5|0. Relay 5|0, upon energizing, at armature 544 grounds conductor |65 by way of armature 565 and maintains the cut-off relay 5|2 in operated position. At armature 544 and resting contact relay 5|0 opens the circuit of relay 509 which accordingly deenergizes. After an interval relay 501 deenergizes and at armature 539 opens the circuit to relay 5|!) which accordingly deenergizes after an interval. In the local connector relay |10 is short circuited by the direct ground connected to conductor |65 by way of armature 544 to cause this relay to deenergize. After an interval relay 5 0 deenergizes and removes ground` from conductor |05 and opens the circuit of cutoi relay 5|2. In the meantime in the local connector relay |10 deenergizes and at armature 1| opens the circuit to relay |02 which deenergizes. At armature |12 opens the circuit to relay |05 which deenergizes. Relay |02, upon deenergizing, at armature 3 opens the circuit to relays |03 and |05 which accordingly deenergizes, and at armature 4 opens the circuit to relay |0| which deenergizes after an interval. At arma- Vcircuit for relay |06.

control operator is signalled in the same manner as previously described. After answering the call the control operator then operates the connector to position the wipers opposite the level of toll li-nes in response to dialling the digits corresponding to the group of toll lines. Assuming thelocal connector in Fig. 2 to be the local connector in use, then when the wipers are raised opposite the toll level, normal post springs |51 close. The closure of normal post springs |51 prepares the In'the same manner as previously described the toll operator nowV rotates the Wipers of the local connector to an idle toll line in the group. Assuming now that the toll line shown in Fig. 6 is the toll line taken into use, then when series relay 3|| in the common equipment deenergizes after the Vdialling period and grounds the wiper |52 a circuit is completed for energizing relay |0 in the toll trunk as follows: from ground by way of armature 350 and resting contact, conductor |89-, armature |29, wiper |52, bank contacts 583, conducto!!` |62, armature 545, and through the vwinding of relay 5|0 to battery. At armature 544 relay 5|0 completes an obvious circuit for energizing the cutoff relay 5|2 of the toll line circuit and at Varmature 545 Vprepares the circuit of relay 501. Relay 5 |'2, upon energizing, at armature 555 connects ground by way of armature 544 to conductor |65 to busy this line in the finder banks. At armature 564 relay 5|i2 disconnects line relay 5|| and at armature 565 opens a point in the circuit to the vstart lead 30. The control operator now operates her two-way key to monitor position andV then to ringing position to cause the operation of relays 30|, 303, 3|4, and 308 as previously described. By the operation of ringing relay 308 ringing current is connected over the wipers |5| and |54 in the manner previously described and thence by way of armatures 54| and 542 and. their resting contacts to the winding of relay 505. Relay 505 energizes and at armature 533 completes the circuit -for energizing relay 50|. At armatures 525 and 521 relay 50| connects ringing current over the toll trunk conductors 590 and 59| and through the repeating coil RC4 to operate the drop at the tol-lv operators position. After ringing the toll operator the control operator restores the two-way key to its normal position thereby interrupting the application of ringing current to the toll lines to cause the deenergize.- tion of relay 505. Relay 50.5, upon deenergizing, opens the circuit of relay 50| which likewise deenergizes. At armatures 525 and 521v relay 50| prepares the circuit for relay503.

In response to theoperation of the drop the toll operator inserts theplug of her cord circuit in-to jack J to open the drop and restore the same. At jack springs 52| a circuit is completed for energizing relay 503 as follows: from ground through the lower windings of relays 503 and 504, lower left-hand winding of repeating coil RC5, resting contact and armature 521, conductor 59|, lower right-hand winding of repeating coil RC4, jack springs 52 I, upper left-hand Winding of reacta-'rac peating coil RC4, conductor l59.0, armature 525 and resting contact, upper `left-hand Winding of repeating coil RC5 and through the upper windings of relays 504 and 503 to battery. At armature y53| relay 503 completes a circuit for energizing relay 502. At armature 529Y relay 502 completes the circuity for energizing relay 501 as follows.: ground by way `of armature 529 and working contact, normally closed springs controlled by armature 53B, armature 545 and Working contact and through the winding of relay 501 to battery. At armature 538 relay 501 completes the locking circuit for itself from grounded armature 529. When the toll operator answers and is informedof the desired connection the control operator disconnects by restoring the key K to .cause the operation ofthe cut-through relay |05 andthe release of the common equipment as previously described.. Relay |05, upon energizing, at armature |39 grounds wiper |52 to maintain relay 5|0 in operated position. At armature |40 completes the locking circuit for itself as well as opening the circuit of relay |04, at armature |4| completes a circuit for energizing relay |06 through the normal post springs |51, and at armature |45 prepares a point in the circuit to relay |02. Relay |06, upon energizing, disconnects the repeating coil and connects the calling subscriber direct to the toll line by way of wipers |5| to |154, inclusive.

After completion of the desired connection and when the calling local R. C. X. subscriber ringsA off, a circuit is completed for operating the relay 505 in the toll trunk as follows: ringing current extends from the calling subscriber over the heavy talking conductors to armatures |43 and |41 and their Working contacts, wipers |5| and |54, connector banks 58l| and 582, conductors |6| and |64, armatures 54| and 542 and Ytheir resting contacts, and through the right-hand windings of repeating coil RC5 and relay 505. Relay 505 at armature 533 completes the circuit for energizing relay 50| and the latter relay at armatures 525 and 521 connect ringing current from the direct generator source over the conductors 590 and 59| through the repeating coil RC4 to the toll operators cord circuit to operate the supervisory disconnect signal in the well known manner. The toll operator in response to this disconnect signal is advised that the conversation is terminated, and if desired may rering the calling subscriber. In response to the operation of the supervisory signal the toll operator wil-l remove the plug of her cord circuit from the jack J, .thereby at jack springs 52| opening the circuit to relay 503. In response to the deenergization of relay 503, relay 502 deenergizes after an interval. ing contact relay 502 opens the locking circuit of relay 501 and at its resting contact momentarily completes a holding circuit for relay 5|0 by way of armature 539 for the period of time it'takes relay 501 to deenergize. Relay 501 in addition to being slow to operate is likewise slow to release. At armature 530 relay 502 momentarily grounds conductor |63 by way of armature 540 to complete an energizing circuit for release relay |02 in the local connector, as follows: from ground by Way of armature 530, armature 540, conductor |63, bank contact 504, wiper |53, armature |45 and through the winding of relay |02 to battery. Relays |02 and |-0'| in the local connector energize in the same manner as previously described. In the toll trunk relay 501 deenergizes after an interval and at armature 540 opens the circuit At armature 529 and its Work-V to relay |02. In response to the deenergization of relay |02 relays |63 and |05 deenergize. At armature |4| relay |05 opens the circuit of relay |96 which accordingly deenergizes and at armature |39 opens the circuit to relay 5|0 which like- Wise deenergizes in case armature 539 is now open. The local connector restores to its normal position in the saine manner as previously described and the toll trunk and local connector may thereafter be used in other calls.

The control operator is signalled at .a time when all of the local connectors are busy either due to such connectors being actually in use, or due to the local subscribers failing to release the same after disconnection. The all link busy relay 208 is normally energized over the chain conductor 69 which extends to all the local connectors and is connected to ground by way of armatures ||1, off normal springs |22, and springs |24 of the busy key in all the local connectors. When all of the local connectors are busy all of the ground connections are disconnected from conductor 69 with the result that the all link busy relay 208 deenergizes. Relay 208, upon deenergizing at armature 234 prepares a point in the circuit for connecting the busy tone conductor to the control trunk, at armature 234 disconnects ground from the multipled bank contacts accessible to wiper 255 to provide stopping positions for the wipers of the distributor, at armature 231 and working contact opens a point in the circuit to relay 203 and at its resting contact prepares a circuit through the lower winding of relay 2||, and at armature 233 prepares a point in the circuit through the upper winding of relay 209. When the operator releases after completing the call which took the last available idle local connector, relay 306, upon deenergizing completes a circuit for energizing relay 2|| as follows: from grounded conductor 262, armature 232 and resting contact, conductor 213, armature 330, conductor 28|, armature 231 and resting contact, and through the lower winding of relay 2| to batt-ery. The relay 2| upon energizing, at armature 248 connects the busy tone lead to conductor 268, at armature 250 completes a locking circuit through its upper winding from grounded armatures 24| and 235, at armature 241 connects grounded armature 240 to yconductor 269, at armature 25| completes an energizing circuit through the lower winding of relay 201 and at armature 285 prepares a circuit for relay 209. At armature 23| relay 201 completes a locking circuit through its lower winding from grounded conductor 264, at armature 229 opens a point in a circuit to motor magnet 40|, at arrature 232 and resting contact opens a point in the original energizing circuit of relay 2| and at its working contact completes the previously traced circuit for energizing relay 430. In the same manner as previously described relays 430 and 43| operate to signal the control operator at the remote operating center. The control operator answers by operating the key K and receives busy tone indicating that all of the connectors are busy. The busy tone circuit may be traced as follows: from the busy tone lead 223, .armature 234, armature 238, resting contact and armature 244, armature 248, conductor 268, through the right-hand windings of the repeating coil RC! conductor 269; armature 241, armature 243 and resting contact, to grounded armature 240. Busy tone is induced into the left-hand windings of the repeating coil RCI, and thence over the control trunk conductors 45| and 452 to the operators head-set,

In order to cut off the busy tone the operator dials the digit 1 and in the same manner as previously described line relay 302 follows the impulse received. Upon the deenergization of line relay 302 said relay at armature 3|8 and resting contact completes a circuit by way of armatures 323 and 348 for energizing the series relay 3||, and by way of armature 324, conductor 219, armature 285, armature 233 and resting contact compl-etes a circuit through the upper winding of relay 209 to battery for energizing the latter relay. At armatures 238 and 240 relay 209, upon energizing, disconnects the busy tone from the control trunk, at armature 239 completes a locking circuit through its lower winding from grounded conductor 218, at armature 242 prepares a point in the circuit to motor magnet 40|, at armature 252 opens a point in the original energizing circuit of relay 430, and at armature 289 opens the locking circuit of relay 43| to cause the latter relay to deenergize. Series relay 3|l, upon energizing, at armature 350 and working contact, completes the energizing circuit for relay 3|2 which energizes and at armature 35| prepares the circuit for relay 3|3. At the end of the impulse, series relay 3|| deenergizes and at armature 350 and working contact removes the short circuit from around relay 3|3 whereupon relay 3|3 energizes in series with relay 3|2 from ground-ed lock conductor 390. Relay 3|3, upon energizing at armature 354 prepares the circuit for motor magnet 40| of the supervisory switch. Relay 430, upon deenergizing, at armatures 434, 435, and 436 connects the wipers of the supervisory switch to the common equipment.

In order to supervise the local connection and determine if the local connectors are in actual use the control operator now dials the digit 1 to step the wipers of the supervisory switch into engagement with the bank contacts terminating the rst local connector. When line relay 302 is deenergized in response to this impulse a circuit is closed by way of armatures 3|8 and 324, conductor 219, armature 242, conductor 280, armature 354, conductor 216, and through the winding of supervisory motor magnet 40| to battery. In response to the energization and deenergization of motor magnet 40| the wipers of the supervisory switch are now operated into engagement with their first set of bank contacts, wiper 404 being connected to conductor 14, wiper 405 being connected to conductor 12, and mper 406 being connected to conductor v13. Since relay 43| is not energized at this time the control trunk is bridged directly across the talking conductors of the first local connector by way of armatures 435 and 436. The operatorcan now hear if any conversation is taking place and in case she does not hear any conversation she will challenge and if no response is given to her challenge she will operate either the two-way monitor and ring key. In case the first local connector is in use the operator will hear such conversation or will receive a response to her challenge. Since this local connector is in use the control operator will again dial the digit 1 to reoperate relay 302 to cause the motor magnet 40| of the supervisory switch to step the wipers to the second local connector. The control operator continues to supervise all of the remaining local connectors and releases all such connectors not in actual use in a manner to be described hereinafter. The rectifier 490 is bridged across the wipers 405 and 406 of the supervisory switch in Order to prevent dial impulses from interfering with or disturbing the existing connections encountered by the wipers of the supervisory switch.

' ential relay 30|, relay |0| in the local connector connected tol the wipers of the supervisory switch -isV operated over the following circuit; from ground by way ofV armature 3|6, conductor 215, armature 434 and resting contact, wiper 404 in engagement with the bank contact terminating conductor 14 of the local connector in operated position but not in'use, and from thence through the winding of relay |V0| to battery. Relay |0| in the local connector, upon energizing,rat armature |56 closes a, partial sho-rt around the winding of relay |10 to cause the latter relay to deenergize, if energized, and' at armature ||2 opens the lockingv circuit ofrelays |03 and |05 to cause these relays to deenergize and release the local connector in the same mannery as previously described. In a similar manner each local connector Vsupervised by the contro-l operator and not inV actual' use is released in this manner by the operator.

As soon as one of the local connectors becomes idle ground is connected to the chain lead 69 by such idle connector to cause the energization of all link busy relay 208. Relay l208, upon energizing, at armature 235 opens one of the multiple locking grounds to relay 2H and connects.y ground to the multiple bank contact accessible to wiper 255 to cause the distributor to hunt for the idle connector. At armature 231 relay 208 prepares a point in the circuit for relay 203 and at arma.- ture233 prepares a point in the circuit to relay 280. The rst time relay 302 deenergzes in response to an'impulse after a connector becomes idle, relay 280 is energized over the following circuit: fromY groundV by way of armature2|8 and resting contact, armature 324, conductor 219., armature 285, armature233, and through the Winding of relay 280 to battery. This impulse of current, therefore, Vin addition to operating the Vwipers of the supervisory switch, also causes the operation of relay 280'. At armature 24| relay 280 opens the locking circuit of relay 2| which accordingly deenergizes. Relay 2| I, upon de- Y energizing, at armature 25|, opens the original energizing circuit of relay 201, so that therlatter Y Y relay will restore when the operator disconnects from the controltrunk. At armature 285 relay V2| opens the circuit to relay 280 to prevent the reenergization of relay 280. After supervising all lof the local connectors the operator disconnects thereby opening the circuit of Vrelay 302. Relay 302 and later relay305 deenergize. At armature 322 relay 305, upon deenergizing opens the circuit of relay 209 which accordingly deenergizes and at armature 326 disconnects ground from conductor 264 to cause the release of relay 201..

In case the operator should disconnect without supervising the local connectors then relay 208 is maintained in its deenergized position. Relay 2H is maintained in energized position from amature 235 andresting contact. Relay 201 is maintained energized from armature 25|. When relay 209 releases in response tol the deenergization of relay 305 relay 430 is reoperated by way of armatures 232 and 252 to signal the control opera-tor over the previously traced circuit. From the .foregoing it will be seen that the Vcontrol operator must necessarily supervise the local connectors and release one or more connectors not in actual use.

In case a fuse blows, the battery charger fails, or a connector fails to release properly a relay group (not shown) is arranged to ground alarm conductor 236 in the well known manner customary in automatic systems. When conductor 236 is grounded a circuit is completed by Way of armature 282 for operating relay 2|0. At armature 242 relay 2|0 prepares a circuit for connecting signalling current to conductor 268, at armature 246 completes a circuit for relay 2|| in case relay 201 is not energized, at armature 245 opens a point in the circuit to relay 203. If no call is in progress relay 2|| is energized over the following circuit: from ground by way of conductor 262, armature 232 and resting contact, conductor 213, Yarmature 330, conductor 28|, armature 246, and through the lower winding of relay 2|| to battery. At armatures 248 and 241 relay 2|| connects the generator conductor 15 by way of condenser M, Working contact and ar'- o mature 244 to conductor 268, and thence through the winding of repeating coil RCI back to conductor 269 and thence by Way of armature 241, armature 243 and working contact, to generator return conductor 16. Ringing current is induced into the left-hand winding of repeating coil RCI in order to advise the operator, when she answers, of the trouble condition in the R. C. X. At armature 250 relay 2|| completes a locking circuit for itself from grounded armature 24| and a't armature 25| completes a. circuit through vthe lower windingl of relay 201 to energize the latterrelay. Relay 201, upon energizing, at armature 23| completes its own locking circuit, and at armature 232 and its working contact completes the circuit for operating relay 430 to signal the control operator in the same manner as previously described. When the operator answers Vorder to remove the tone the operator disconnects by restoring her key K, thus opening the circuit to relay 302. Relay 302 opens the circuit to relay 305, butbefore relay 305 is deenerr gized the following circuit for relay 280 is completed from ground by way of armature 3|8 and resting contact, armature 324, conductor 219, armatures 285 and 284 and through the winding of relay 280 to battery. `Relay 280 at armature 283 locks'itself to the alarm conductor 236, at armature 282 opens the circuit of relay 2 0 which accordingly deenergizes and at armature 24| opens the locking circuit of relay 2||. Relay 2H, upon deenergizing, at armatures 248 and 241 disconnects the alarm tone from repeating coil RCI, at armature 285 opens the original energizing circuit to relay 280, and at armature 25| opens the original energizing circuit of relay 201. Relay 2|0, upon deenergizing, at armatures 244 and 243 opens a further point in the circuit Y 

